1. Field of the Invention
This invention relates generally to a hollow-fiber permeability apparatus, and more particularly to a hollow-fiber permeability apparatus in which a permeating region of a housing contains a bundle of hollow fibers, and materials can selectively permeate through the membranes formed by the permeable walls of the hollow fibers, between a fluid flowing along the exteriors of the hollow fibers, and another fluid flowing the interiors of the hollow fibers. The permeation may be based on the principles of osmosis, dialysis, ultrafiltration, reverse osmosis or the like.
2. Description of the Prior Art
For example, a conventional hollow-fiber permeability apparatus is used for blood dialysis in an artificial kindney, in which toxic materials are removed from the blood of a patient suffering from renal failure or medicinal poisoning. Such apparatus is also used in an artificial lung, in which oxygen and carbon dioxide are exchanged with each other to increase the blood oxygen content.
FIG. 1 shows one example of the conventional hollow-fiber permeability apparatus. A cylindrical housing 1 is packed with a bundle 3 of numerous hollow fibers 2. The hollow fibers are fixed at upper and lower ends with potting materials 4. The cut ends of the hollow fibers 2 are open to compartment 6 formed by cover 5. Blood 7 is introduced into the compartment 6 of the housing 1 through an blood inlet tube 8 connected to the upper cover 5. The blood 7 is distributed to the hollow fibers 2, and flows into the interiors of the hollow fibers 2. It is collected into a lower compartment 10 formed by a lower cover 9, and discharged through a blood outlet tube 11 from the housing 1.
On the other hand, dialysate 12 is introduced into the housing 1 through an inlet tube 13 for dialysate formed in the lower end portion of the housing 1, and flows upward along the exteriors of the hollow fibers 2. On the basis of Donnan's membrane equilibrium, metabolic waste or excess ions permeates through the wall membranes of the hollow fibers 2 from blood 7 to dialysate 12, or necessary ions permeates through the wall membranes of the hollow fibers 2 from dialysate 12 to blood 7, due to the concentration differences between blood 7 and dialysate 12. Or water is removed from blood 7 by ultrafilteration. After dialysis, the dialysate 12 is discharged from the housing 1 through an outlet tube 14 for dialysate.
The above described hollow-fiber permeability apparatus is physically beneficial to a patient during dialysis. It is easy to handle, and superior in withstanding pressure. The security is good. Thus, the hollow fiber permeability apparatus has many advantages.
However, 10,000 or more hollow fibers whose outer diameter and inner diameter are about 300 .mu. and 250 .mu. are closely packed in the housing 1. Accordingly, it is difficult for dialysate to penetrate uniformly through the whole of the bundle 3 of hollow fibers 2. The dialysis efficiency is extremely low in the central portion of the bundle 3. A uniform dialysis cannot be expected.